I bought a TV in November and installed it last month worked fine but last night turned it on sound but no picture so what do I do

Check you HDMI cables, often time spending a bit extra on an HDMI cable helps. Ensure the cable is connected to the system box and the TV. TRY disconnecting and reconnecting

Do you have the sound from your DVD or cable connect?

First, check your cable connections. Simplest solution is usually a bad or loose hdmi.